This invention relates to stratified fuel injection systems for rotary piston internal combustion engines and, more specifically, relates to an improvement in such systems having a fuel injection nozzle which coacts with an igniter to ignite the fuel discharging from the fuel injection nozzle. This type of stratified charge fuel injection system is disclosed in the following U.S. patents:
U.S. Pat. No. 3,246,636--Bentele--Apr. 19, 1966
U.S. Pat. No. 3,698,364--Jones--Oct. 17. 1972
U.S. Pat. No. 3,894,518--Gavrun et al--July 15, 1975
As explained in the above mentioned Gavrun et al U.S. patent, stratified charge fuel injection systems for rotary internal combustion engines are a recognized approach to the solution of exhaust pollution and fuel consumption of rotary internal combustion engines. As also explained in the aforesaid Gavrun et al patent, stratified charge operation contemplates a fuel-air mixture or charge in each working chamber of the engine which is not a uniform or a stoichiometric mixture and instead has at least one region where the fuel-air mixture is relatively rich. In the fuel injection-ignition devices where the fuel nozzle is located inwardly from the working chamber only sufficiently far enough to provide space for the igniter, it has been found that the recess common to the nozzle and igniter tends to be built up with carbon deposits which interferes with the desired fuel spray pattern past the igniter and into the working chamber. This buildup of deposits is attributed to the relatively cool surfaces of the common recess from which heat is conducted through the housing. Also the cool surfaces of the common recess have been found to chill the fuel and entrained air flowing past the surfaces and resulting in some incomplete combustion and/or firing irregularity. These problems are not present in precombustion chamber systems such as exemplified in the U.S. patent to Bentele, U.S. Pat. No. 3,387,595 dated June 11, 1968 where a portion of the precombustion chamber is insulated from the engine housing. In these systems, the fuel-air mixture is confined to the vicinity of the spark plug so that the chilling effect has minimal adverse effect on achieving light-off with regularity. In fact, effort is made in precombustion chamber systems to cool the chamber in varous ways such as fins and cooling fluid passages in the vicinity of the chamber. This chilling effect on the fuel-air mixture is of particular concern in achieving optimum firing regularity and engine performance where the nozzle and igniter coacts to produce a pilot flame to ignite the main fuel charge emitted into the working chambers by a second nozzle.
Accordingly, it is an object of this invention to provide an improved stratified charge fuel injection system for a rotary piston, internal combustion engine wherein more complete combustion of fuel is achieved with the attendant reduction in pollutants in the exhaust emissions and improvement in fuel economy.
It is a further object of the present invention to provide an improved stratified charge fuel injection system for a rotary piston internal combustion engine wherein regularity of firing (ignition) is optimized.